How can we improve?

Documents only

Since the Document-Feature could be very helpful as an alternative way of sharing files between user accounts, we would like to suggest making it possible to deactivate mail, calendar, notes and task for individual accounts. This would make it possible to (only) share files with certain users, without giving access to a fully working e-mail-account.

Hello Christian,
You can disable Calendar, Notes and Task now.
Go to the MDaemon\WorldClient folder.
Open the Domains.ini
Add a section at the bottom for each user you are wanting to limit access to. User being the user name for that account.
[User:UserOverrides]
EnableCalendar=No
EnableTasks=No
EnableNotes=No

Save changes and restart WorldClient. This would disable Calendar, Tasks and Notes.
As for email access you can add restrictions inside of MDaemon to not allow them to accept or send emails. Not sure if you are not wanting to have access to email in WorldClient only or No access to email at all.